Business Combinations and Asset Acquisitions - Pro Forma (Details) - Umpqua Bank and Columbia Banking System Merger - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022
Asset Acquisition [Line Items]
Business acquisition, pro forma net interest income	$ 1,951,561	$ 2,056,167
Business Acquisition, Pro Forma Non-interest Income	237,764	288,417
Business Acquisition, Pro Forma Net Income (Loss)	633,719	$ 550,727
Business Combination, Acquisition Related Costs - Combined for proforma	$ 199,700